Armyworm threatens bumper harvest:
FARMERS have warned that the national yields for an otherwise good 2016 - 2017 cropping season are in great jeopardy as they are failing to control the fall armyworm outbreak.
The fall armyworm, an avid crop-eating caterpillar of American origin, arrived in Southern Africa and subsequently Zimbabwe late last year and has so far invaded maize fields in almost all the 10 provinces.
And mitigating efforts have brought little success so far as the invasive pest is said to be pesticide-resistant and more diverse in its food choice than the common stalk-borer.
“The situation is very bad at the moment because farmers have tried everything but are failing to control the pest,” said president of Zimbabwe Commercial Farmers Union, Mr Wonder Chabikwa.
“It is resisting all known and registered chemicals and we are now afraid that our harvests will be significantly affected. The most dreadful thing about these caterpillars is that we have little knowledge about them and their behaviour is hard to predict. So what we are saying is that we need Government to intervene because this is a potential national disaster.”
Mr Chabikwa said unlike the stalk borer which attacks the crops when they are still small, the fall armyworm attacks at all levels, even when the crop is grown and difficult to spray. He said the crop which was planted late is the one in particular danger and he urged Government to commence aerodrome spraying.
Mr Chabikwa also said available chemicals such as Carbaryl 85 Wettable Powder had proved ineffective in some instances with some agronomists recommending a combination of pesticides to deal with the pest.
Director of Zimbabwe Farmers Union, Mr Paul Zakariya, concurred saying the fact that knowledge is lacking warrants an all-stakeholder’s intervention which includes farmers, researchers, agronomists and climate scientists.
“The situation is certainly bad than what many people think,” he said.
“So there is need to deal with this problem at a national level because the individual farmers have failed. Noone really has the knowledge about the pest, for instance you may spray the maize field but you won’t get rid of the worm entirely because in the grass it is there, in your tobacco and your other crops it is there.”
We need powerful chemicals and aerodrome spraying, not for this season alone but also for the future to ensure that we get rid of it once and for all.
In Southern Africa, the pest has affected Zimbabwe, Zambia, Malawi, Mozambique and South Africa. It has also swept large swathes of maize in some parts of West and Central Africa.
Drought and record high temperatures in the 2015-16 season are said to have created conducive conditions for foreign pests such as the fall armyworm.
Officials from the Food and Agriculture Organisation (FAO) have already warned that the fall army worm is threatening food security in affected countries.
“If not controlled in the countries affected, it will have devastating effects not only in those countries, but neighbouring countries too, because the spread capacity of this pest is very high,” said David Phiri, the coordinator of FAO’s operations in Southern Africa.
“The problem is that if you have had, like we have had here in southern Africa, two droughts, it provides a conducive environment for the army worms to be very active when the rains come.”
Fall armyworm was first reported in West and Central Africa at the start of 2016. The pest has since jumped the equator into Burundi, Zambia, Zimbabwe and Malawi. In Zimbabwe it was first reported by farmers in Matabeleland provinces and has spread to other provinces and areas such as Glendale, Shamva, Chegutu and Banket.
According to the Research Services Division in the Ministry of Agriculture, Mechanisation and Irrigation Development; the fall armyworm is new in Zimbabwe and is a voracious feeder during an outbreak.
“Caterpillars of fall armyworm seem to be much more damaging to maize than most other African species,” said researchers.
The research department also warned that the fall armyworm is at present dominant in West Africa but will soon be able to colonise most of tropical Africa.
The department also cautioned that hobnobbing between use of selected insecticides and non-selective use will lead to the emergence of resistant pest populations.
“Alternated application of insecticides such as pyrethroids, carbamates and organophosphates are recommended as immediate measure,” researchers recommended.
“Controlling of fall armyworm with Carbaryl 85% WP at high dosage rates of 300-400g/15 litres water to effectively control the pest at full cover spray is advised.”
In Mexico, where the worm originated, dichlor-diphenyl-trichloroethane (DDT) was used to fumigate the pest which has up to 12 life cycles.
The caterpillars, which are brown in colour, costs Brazil about $600 million a year to control. Fall armyworm has a remarkable dispersal capacity (the movement of animals, plants, fungi, bacteria, pest, etc from their birth site to their breeding site as well as the movement from one breeding site to another) of over 2 000km per year.
According to researches by University of Florida, the species seemingly display a very wide host range, with over 80 plants recorded, but clearly prefers grasses.
“The most frequently consumed plants are maize, sorghum, Bermuda grass, and grass weeds such as crab grass.”
However, the fall armyworm outbreak did not entirely catch the authorities by surprise. Last year, the International Red Locust Control Organisation for Central and Southern Africa warned of alien pests coming into Sadc countries.
“Forecasts show that all migratory pests will be of great concern next year and may affect food security in Southern Africa,” the organisation said then.
Consequently, Zimbabwe now faces a new threat from an invasion of red locusts that attack maize and wheat amid fears the insects could greatly reduce this year’s yields. Zimbabwe, like other countries in the Sadc region, is coming out of a severe drought which left some four million people food-insecure.
While the situation is expected to gradually improve by the time of harvest, United Nations agencies warn that food aid is still required in most parts of the country, particularly Matabeleland.
Meanwhile, good rains are expected to persist until March when most maize crops are expected to have ripened.
“In our interactions with the Met Department, they tell us that the rains will continue until March,” Mr Chabikwa has said.
“And if that is the case then I can confidently say it will be good harvest but we have to deal with this current threat of the fall armyworm to maximize on our yields. Otherwise there should be no fears that the continued rains will damage the ripened crop because much of the crop is still in need of more rains.”